Auto ISO is one of many helpful features that has become a core feature of digital cameras. Back in film days, you were generally confined to the ISO of the roll of film that was loaded. Digital cameras, though, can have a different ISO for each shot. And better yet, it’s adjusted silently on the fly by the camera itself.
Olympus is now OM System
In 2020-21, the photography business of iconic camera brand Olympus was spun off and sold. The core remaining Olympus brand is focusing on medical and scientific products. The camera and photography side was then rebranded as OM System, with the first cameras and lenses under that brand coming out at the end of 2021.
On the OM System OM-5, the Auto ISO feature works well out of the box with the default settings, but there are also some ways to tweak its behavior, such as limiting the maximum ISO it will use. Here’s a rundown of the available options and how to use them.
Available Auto ISO Settings on the OM System OM-5
You can find the settings for the Auto ISO feature under the gear icon.
Gear (cog) icon > E1 > ISO-Auto Set
Under that, you’ll find two further sets of options. The first is Upper Limit / Default. This sets two things about the Auto ISO.
The Upper Limit refers to the ISO ceiling when using Auto ISO feature. Or, put it another way, it’s the maximum ISO that Auto ISO will go to. The default is ISO 6400. But perhaps you might want to set it lower than that to make absolutely sure you don’t run into image noise because you’re working with a stock agency, for example (stock agencies are often very strict about image noise).
There is something important to know about this setting: ISO 6400 is both the default setting and also the maximum that you can be used with Auto ISO. That is, you can change it to lower than 6400, but you can’t set it higher. 1
What that means is that you want to take advantage of the full ISO range of the OM-5, which goes all the way up to ISO 25600, you can’t do it while using the Auto ISO feature–you’ll need to set that ISO manually.
The Default setting is the baseline ISO used. The default is ISO 200, which is a compromise of image quality and sensitivity speed that’s weighted toward image quality.
Using the default setting of 200 as an example, what it means is that it will first try to expose with an ISO of 200. But if the light and the combination of shutter speed and aperture won’t support that, then it will move up to the next closest ISO that will work. Or, put another way, it will favor ISO 200 for each shot and only deviate from that if there’s not enough light (in combination with the other parts of the exposure triangle, shutter speed and aperture).
An example of where you might want to set this higher is if you want to encourage the camera toward faster shutter speeds when using P or A shooting modes.
Lowest S/S Setting
The lowest shutter speed option sets the threshold for shutter speed when making the calculation on exposure and Auto ISO. So it’s similar to the Default setting above but this time applies to shutter speed rather than ISO. But it still affects ISO because it’s all part of the symbiotic exposure triangle calculation.
Where this is most important is in setting a floor to minimize any effects of camera shake. The Auto setting will calculate the minimum shutter speed used in the calculation based on the focal length of the lens being used. 2
But you can also override the Auto setting and assign a minimum shutter speed of 1/250sec. This can be especially effective when trying to freeze action or ensure that camera shake doesn’t become a problem.
The separate ISO-Auto setting adjust a related option, but it’s a simple one. It changes which shooting modes the Auto ISO feature is available in.
The default is in Program/Aperture Priority/Shutter Speed Priority/Manual modes.
But you can choose to leave Manual off that list. It’s a small tweak, but it’s one I like. That’s because when you shift to manual mode, there’s a good chance you’re aiming for something very deliberate. You might be wanting to create some motion blur, for instance, so you don’t want Auto ISO fighting against you. Another place I find it useful is if I’m shooting a sequence where I need identical exposure from shot to shot, such as shooting panels to be stitched for a panorama.
- There are some other setting combinations that affect the available maximum ISO here, such as if the live ND (neutral density) filter is enabled.[↩]
- I haven’t tested for the precise ratio used on the OM-5, but on other cameras it’s typically around 1:1, which is based on the old photography rule of thumb of using a shutter speed that’s at least as fast as the focal length to minimize the effects of camera shake. So shooting with an effective focal length of 50mm, for instance, would allow for a minimum shutter speed for 1/50 of a second. And a telephoto lens focal length of 250mm would suggest a shutter speed of 1/250th of a second. (NB: It’s worth noting that this is for effective focal length. On a Micro Four Thirds camera, that means doubling what’s written on the lens. So a Micro Four Thirds focal length of 40mm is an effective focal length of 80mm.) But that rule of thumb doesn’t factor in image stabilization, so there might be a different ratio at work (or even several ratios) on the OM-5.[↩]